Biomimicry of oil infused layer on 3D printed poly(dimethylsiloxane): Non-fouling, antibacterial and promoting infected wound healing

A comprehensive review of the application of 3D-bioprinting in chronic wound management

INTRODUCTION

Chronic wounds require more sophisticated care than standard wound care because they are becoming more severe as a result of diseases like diabetes. By resolving shortcomings in existing methods, 3D-bioprinting offers a viable path toward personalized, mechanically strong, and cell-stimulating wound dressings.

AREAS COVERED

This review highlights the drawbacks of traditional approaches while navigating the difficulties of managing chronic wounds. The conversation revolves around employing natural biomaterials for customized dressings, with a particular emphasis on 3D-bioprinting. A thorough understanding of the uses of 3D-printed dressings in a range of chronic wound scenarios is provided by insights into recent research and patents.

EXPERT OPINION

The expert view recognizes wounds as a historical human ailment and emphasizes the growing difficulties and expenses related to wound treatment. The expert acknowledges that 3D printing is revolutionary, but also points out that it is still in its infancy and has the potential to enhance mass production rather than replace it. The review highlights the benefits of 3D printing for wound dressings by providing instances of smart materials that improve treatment results by stimulating angiogenesis, reducing pain, and targeting particular enzymes. The expert advises taking action to convert the technology's prospective advantages into real benefits for patients, even in the face of resistance to change in the healthcare industry. It is believed that the increasing evidence from in-vivo studies is promising and represents a positive change in the treatment of chronic wounds toward sophisticated 3D-printed dressings.

3D printed drug loaded nanomaterials for wound healing applications

Wounds are a stern healthcare concern in the growth of chronic disease conditions as they can increase healthcare costs and complicate internal and external health. Advancements in the current and newer management systems for wound healing should be in place to counter the health burden of wounds. Researchers discovered that two-dimensional (2D) media lacks appropriate real-life detection of cellular matter as these have highly complicated and diverse structures, compositions, and interactions. Hence, innovation towards three-dimensional (3D) media is called to conquer the high-level assessment and characterization in vivo using new technologies. The application of modern wound dressings prepared from a degenerated natural tissue, biodegradable biopolymer, synthetic polymer, or a composite of these materials in wound healing is currently an area of innovation in tissue regeneration medicine. Moreover, the integration of 3D printing and nanomaterial science is a promising approach with the potential for individualized, flexible, and precise technology for wound care approaches. This review encompasses the outcomes of various investigations on recent advances in 3D-printed drug-loaded natural, synthetic, and composite nanomaterials for wound healing. The challenges associated with their fabrication, clinical application progress, and future perspectives are also addressed.

The applications of 3D printing in wound healing: the external delivery of stem cells and antibiosis

As the global number of chronic wound patients rises, the financial burden and social pressure on patients increase daily. Stem cells have emerged as promising tissue engineering seed cells due to their enriched sources, multidirectional differentiation ability, and high proliferation rate. However, delivering them in vitro for the treatment of skin injury is still challenging. In addition, bacteria from the wound site and the environment can significantly impact wound healing. In the last decade, 3D bioprinting has dramatically enriched cell delivery systems. The produced scaffolds by this technique can be precisely localized within cells and perform antibacterial actions. In this review, we summarized the 3D bioprinting-based external delivery of stem cells and their antibiosis to improve wound healing.

Dressing Materials: A Comprehensive Review

Injury to the skin provides a difficult challenge, as wound healing is a complex and dynamic process. Wound healing process recruits three different phases: inflammation, proliferation, and maturation. The sequence of events involved in wound healing can be affected by numerous disease processes, resulting in chronic, non-healing wounds that give significant discomfort and distress to the patients while draining the medical fraternity of enormous resources. Wound tissue never reaches its pre-injured strength and multiple aberrant healing states can result in chronic non-healing wounds. There is a growing concern about the usage of correct materials for wound dressings. The development of new and effective treatments in wound care still remains an area of intense research. There are a number of wound dressings available in the market. The objective of the article is to enhance knowledge about characteristics of an ideal wound dressing and guide in finding the correct dressing material. It also provides a detailed classification of traditional and modern wound dressings.

Recent advancements in wound management: Tailoring superwettable bio-interfaces

Skin tissue suffering from severe damages fail in self-regeneration. Proper wound dressings are highly demanded to protect the wound region and accelerate the healing process. Although large efforts have been devoted, there still exist disturbing dilemmas for traditional dressings. The exquisite design of bio-interface upon superwettable materials opens new avenues and addresses the problems perfectly. However, the advancements in this area have rarely been combed. In light of this, this minireview attempts to summarize recent strategies of superwettable bio-interfaces for wound care. Concentrating on the management of biofluids (blood and exudate), we described superwettable hemostatic bio-interfaces first, and then introduced the management of exudates. Finally, the perspective of this area was given. This minireview gives a comprehensive outline for readers and is believed to provide references for the design of superwettable materials in biomedical area.

A Review on Antibacterial Biomaterials in Biomedical Applications: From Materials Perspective to Bioinks Design

In tissue engineering, three-dimensional (3D) printing is an emerging approach to producing functioning tissue constructs to repair wounds and repair or replace sick tissue/organs. It allows for precise control of materials and other components in the tissue constructs in an automated way, potentially permitting great throughput production. An ink made using one or multiple biomaterials can be 3D printed into tissue constructs by the printing process; though promising in tissue engineering, the printed constructs have also been reported to have the ability to lead to the emergence of unforeseen illnesses and failure due to biomaterial-related infections. Numerous approaches and/or strategies have been developed to combat biomaterial-related infections, and among them, natural biomaterials, surface treatment of biomaterials, and incorporating inorganic agents have been widely employed for the construct fabrication by 3D printing. Despite various attempts to synthesize and/or optimize the inks for 3D printing, the incidence of infection in the implanted tissue constructs remains one of the most significant issues. For the first time, here we present an overview of inks with antibacterial properties for 3D printing, focusing on the principles and strategies to accomplish biomaterials with anti-infective properties, and the synthesis of metallic ion-containing ink, chitosan-containing inks, and other antibacterial inks. Related discussions regarding the mechanics of biofilm formation and antibacterial performance are also presented, along with future perspectives of the importance of developing printable inks.

Multifunctional 3D printed porous GelMA/xanthan gum based dressing with biofilm control and wound healing activity

Bacterial infections are the major challenges of wound treatment in current clinical applications. In this study, Three-dimensional (3D) antibacterial wound dressing has been fabricated via introducing N-halamine/TiO₂ to gelatin methacrylate and xanthan gum. The prepared 3D printed dressings showed ideal swelling ratio and excellent water uptake efficiency. TiO₂ nanoparticles were introduced by in-situ to improve the ultraviolet stability of N-halamines. The 3D printed GX2-TiO₂-PSPH-Cl prepared dressings containing titanium dioxide retained 0.19% active chlorine after ultraviolet irradiation for 20 min, which was much higher than that of N-halamine dressings without the addition of TiO₂. The 3D printed dressings showed good antibacterial activity, and 100% of Escherichia coli O157:H7 and Staphylococcus aureus were inactivated after 60 min of contact. Furthermore, the biofilm test indicated that the 3D antibacterial dressings were able to inhibit the formation of bacterial biofilm. The 3D printed dressings possess outstanding biocompatibility. Moreover, in vivo data demonstrated that the 3D printed dressings could significantly accelerate wound healing in a mouse model, indicating that the developed 3D printed dressings are ideal candidates for wound treatment.

3D-Printed Products for Topical Skin Applications: From Personalized Dressings to Drug Delivery

3D printing has been widely used for the personalization of therapies and on-demand production of complex pharmaceutical forms. Recently, 3D printing has been explored as a tool for the development of topical dosage forms and wound dressings. Thus, this review aims to present advances related to the use of 3D printing for the development of pharmaceutical and biomedical products for topical skin applications, covering plain dressing and products for the delivery of active ingredients to the skin. Based on the data acquired, the important growth in the number of publications over the last years confirms its interest. The semisolid extrusion technique has been the most reported one, probably because it allows the use of a broad range of polymers, creating the most diverse therapeutic approaches. 3D printing has been an excellent field for customizing dressings, according to individual needs. Studies discussed here imply the use of metals, nanoparticles, drugs, natural compounds and proteins and peptides for the treatment of wound healing, acne, pain relief, and anti-wrinkle, among others. The confluence of 3D printing and topical applications has undeniable advantages, and we would like to encourage the research groups to explore this field to improve the patient's life quality, adherence and treatment efficacy.

Tailoring Materials with Specific Wettability in Biomedical Engineering

As a fundamental feature of solid surfaces, wettability is playing an increasingly important role in our daily life. Benefitting from the inspiration of biological paradigms and the development in manufacturing technology, numerous wettability materials with elaborately designed surface topology and chemical compositions have been fabricated. Based on these advances, wettability materials have found broad technological implications in various fields ranging from academy, industry, agriculture to biomedical engineering. Among them, the practical applications of wettability materials in biomedical-related fields are receiving remarkable researches during the past decades because of the increasing attention to healthcare. In this review, the research progress of materials with specific wettability is discussed. After briefly introducing the underlying mechanisms, the fabrication strategies of artificial materials with specific wettability are described. The emphasis is put on the application progress of wettability biomaterials in biomedical engineering. The prospects for the future trend of wettability materials are also presented.

Hemostatic materials in wound care

Blood plays an essential role in the human body. Hemorrhage is a critical cause of both military and civilian casualties. The human body has its own hemostatic mechanism that involves complex processes and has limited capacity. However, in emergency situations such as battlefields and hospitals, when the hemostatic mechanism of the human body itself cannot stop bleeding effectively, hemostatic materials are needed for saving lives. In this review, the hemostatic mechanisms and performance of the most commonly used hemostatic materials, (including fibrin, collagen, zeolite, gelatin, alginate, chitosan, cellulose and cyanoacrylate) and the commercial wound dressings based on these materials, will be discussed. These materials may have limitations, such as poor tissue adhesion, risk of infection and exothermic reactions, that may lessen their hemostatic efficacy and cause secondary injuries. High-performance hemostatic materials, therefore, have been designed and developed to improve hemostatic efficiency in clinical use. In this review, hemostatic materials with advanced performances, such as antibacterial capacity, superhydrophobicity/superhydrophilicity, superelasticity, high porosity and/or biomimicry, will be introduced. Future prospects of hemostatic materials will also be discussed in this review.

Dual-functional hybrid quaternized chitosan/Mg/alginate dressing with antibacterial and angiogenic potential for diabetic wound healing

BACKGROUND

Clinic treatment of diabetic foot ulcers (DFUs) is considerably challenging. Impaired wound healing may be caused by poor vascularization and dysfunction of the extracellular matrix, which leads to poor re-epithelialization and increased risk of infection. In this study, we evaluated the treatment potential of a functional dressing comprising quaternized chitosan (hydroxypropyltrimethyl ammonium chloride chitosan) and magnesium (Mg) on DFUs.

METHODS

Dressings were prepared by vacuum freeze-drying. The cellular proliferation, migration, and angiogenesis potential of the functional dressings were determined in vitro. Methicillin-resistant Staphylococcus aureus (MRSA, ATCC43300) and methicillin-resistant Staphylococcus epidermidis 287 (MRSE287) were used to evaluate the antibacterial efficiency of the dressings. Finally, a diabetic rat model with infected wounds was used to further evaluate the effects of functional dressings on the healing of DFUs.

RESULTS

Functional dressings facilitated the migration of human dermal fibroblasts and human umbilical vein endothelial cells (HUVECs), while also stimulating angiogenesis in HUVECs. Additionally, the functional dressing could effectively eradicate MRSA and MRSE, exhibiting excellent antibacterial ability against drug-resistant bacteria. The results of in vivo microbiological and histological tests demonstrated effective anti-infection ability and wound-healing potential of this functional dressing.

CONCLUSIONS

The dual-functional dressing exhibited wound-healing ability and anti-infection efficiency, demonstrating potential application prospects in DFU treatment.

TRANSLATIONAL POTENTIAL OF THIS ARTICLE

As one of the common and serious complications of diabetes, DFUs do not heal easily, causing great suffering to patients. Therefore, improvement in the prognosis of DFUs is a crucial clinical need. The dual-functional dressing prepared in this study was proven to improve the treatment of DFUs, both in vitro and in vivo. Considering its urgent clinical necessity and good biocompatibility of its raw materials, such as alginate, Mg, and chitosan derivatives, this dual-functional dressing presents good prospects for clinical translation.

Wound Healing: From Passive to Smart Dressings

The universal increase in the number of patients with nonhealing skin wounds imposes a huge social and economic burden on the patients and healthcare systems. Although, the application of traditional wound dressings contributes to an effective wound healing outcome, yet, the complexity of the healing process remains a major health challenge. Recent advances in materials and fabrication technologies have led to the fabrication of dressings that provide proper conditions for effective wound healing. The 3D-printed wound dressings, biomolecule-loaded dressings, as well as smart and flexible bandages are among the recent alternatives that have been developed to accelerate wound healing. Additionally, the new generation of wound dressings contains a variety of microelectronic sensors for real-time monitoring of the wound environment and is able to apply required actions to support the healing progress. Moreover, advances in manufacturing flexible microelectronic sensors enable the development of the next generation of wound dressing substrates, known as electronic skin, for real-time monitoring of the whole physiochemical markers in the wound environment in a single platform. The current study reviews the importance of smart wound dressings as an emerging strategy for wound care management and highlights different types of smart dressings for promoting the wound healing process.

Recent Progress of Bioinspired Scalephobic Surfaces with Specific Barrier Layers

Bioinspired superwettable surfaces have been widely harnessed in diverse applications such as self-cleaning, oil/water separation, and liquid transport. So far, only a little work is focused on scalephobic capability of those superwettable surfaces. However, the troublesome scale deposition will inevitably be observed in our daily production and life, greatly reducing heat transfer efficiency and inhibiting the liquid transport. To address this annoying problem, as the emerging strategy, specific barrier layers are introduced onto superwettable surfaces to reduce or even avoid the direct contact between scale and the surfaces. In this feature article, we first provide the basic concept of bioinspired scalephobic surfaces with specific barrier layers. Then, we briefly introduce the typical fabrication methods of scalephobic surfaces. Later, we summarize recent progress of bioinspired scalephobic surfaces with specific barrier layers. Furthermore, we point out the guiding theory and criteria for the stability of barrier layers. Finally, we put forward the forecast on the existing problems and future direction in bioinspired scalephobic surfaces.

Recent Advances in the Design of Three-Dimensional and Bioprinted Scaffolds for Full-Thickness Wound Healing

Three-dimensional (3D) printed scaffolds have recently emerged as an innovative treatment option for patients with critical-sized skin wounds. Current approaches to managing life-threatening wounds include skin grafting and application of commercially sourced skin substitutes. However, these approaches are not without several challenges. Limited donor tissue and donor site morbidity remain a concern for tissue grafting, while engineered skin substitutes fail to fully recapitulate the complex native environment required for wound healing. The implementation of 3D printed dermal scaffolds offers a potential solution for these shortcomings. Spatial control over scaffold structure, the ability to incorporate multiple materials and bioactive ingredients, enables the creation of conditions specifically optimized for wound healing. Three-dimensional bioprinting, a subset of 3D printing, allows for the replacement of lost cell populations and secreted active compounds that contribute to tissue repair and recovery. The replacement of damaged and lost cells delivers beneficial effects directly, or synergistically, supporting injured tissue to recover its native state. Despite encouraging results, the promise of 3D printed scaffolds has yet to be realized. Further improvements to current material formulations and scaffold designs are required to achieve the goal of clinical adoption. Herein, we provide an overview of 3D printing techniques and discuss several strategies for healing of full-thickness wounds by using 3D printed acellular scaffolds or bioprinted cellular scaffolds, aimed at translating this technology to the clinical management of skin lesions. We identify the challenges associated with designing and optimizing printed tissue replacements, and discuss the future perspectives of this emerging option for managing patients who present with critical-sized life-threatening cutaneous wounds.

Cryogenically printed flexible chitosan/bioglass scaffolds with stable and hierarchical porous structures for wound healing

Wound healing is a dynamic and well-orchestrated process that can be promoted by creating an optimal environment with wound dressing. An ideal wound dressing material should possess a suitable matrix, structure and bioactive components, functioning synergistically to accelerate wound healing. Wound dressings that allow reproducibility and customizability are highly desirable in clinical practice. In this study, using chitosan (CS) as the matrix and bioglass (BG) as the biological component, a spatially designed dressing scaffold was fabricated from a home-made cryogenic printing system. The micro- and macro-structures of the scaffold were highly controllable and reproducible. The printed scaffold exhibited interconnected and hierarchical pore structures, as well as good flexibility and water absorption capacity, and these properties were not affected by the content of BG. Nevertheless, when the content of BGs exceeded 20% that of CS, the tension strength and elongation rate reduced, but in vitro antibacterial, cell proliferation and migration performance were enhanced. In vivo examinations revealed that the composite scaffold significantly promoted wound healing process, with the group having 30% bioglass showing better wound closure, neovascularization and collagen deposition than other groups. These results indicate that the 3D printed CS/BG composite scaffold is a promising dressing material that accelerates wound healing.

Development of 3D Printed Drug-Eluting Scaffolds for Preventing Piercing Infection

Herein, novel drug-eluting, bio-absorbable scaffold intended to cover piercing studs is introduced. This “biopierce” will stay in human tissue following piercing, and will slowly release an antimicrobial agent to prevent infection while the wound heals. Nearly 20% of all piercings lead to local infection. Therefore, it is imperative to develop alternative methods of piercing aftercare to prevent infection. Biopierces were made using mupirocin loaded poly-lactic-co-glycolic acid (PLGA) biomaterial ink, and a low-temperature 3D printing technique was used to fabricate the biopierces. Proton nuclear magnetic resonance (¹H NMR) spectroscopy was used to confirm the complete removal of the solvent, and liquid chromatography high-resolution mass spectrometry (LC-HRMS) was used to confirm the structural integrity of mupirocin and to quantify the amount of the released drug over time. The efficacy of the biopierces against Staphylococcus aureus, one of the most common piercing-site pathogens, was confirmed over two weeks using in vitro antimicrobial susceptibility testing.

One-Step Preparation of an AgNP-nHA@RGO Three-Dimensional Porous Scaffold and Its Application in Infected Bone Defect Treatment

Background

Bactericidal capacity, durable inhibition of biofilm formation, and a three-dimensional (3D) porous structure are the emphases of infected bone defect (IBD) treatment via local scaffold implantation strategy.

Purpose

In this study, silver nanoparticle (AgNP)-loaded nano-hydroxyapatite (nHA)@ reduced graphene oxide (RGO) 3D scaffolds (AHRG scaffolds) were designed to alleviate bone infection, inhibit biofilm formation, and promote bone repair through the synergistic effects of AgNPs, RGO, and nHA.

Materials and Methods

AHRGs were prepared using a one-step preparation method, to create a 3D porous scaffold to facilitate a uniform distribution of AgNPs and nHA. Methicillin-resistant Staphylococcus aureus (MRSA) was used as a model-resistant bacterium, and the effects of different silver loadings on the antimicrobial activity and cytocompatibility of materials were evaluated. Finally, a rabbit IBD model was used to evaluate the therapeutic effect of the AHRG scaffold in vivo.

Results

The results showed successful synthesis of the AHRG scaffold. The ideal 3D porous structure was verified using scanning electron microscopy and transmission electron microscopy, and X-ray photoelectron spectroscopy and selected area electron diffraction measurements revealed uniform distributions of AgNP and nHA. In vitro antibacterial and cytocompatibility indicated that the 4% AHRG scaffolds possessed the most favorable balance of bactericidal properties and cytocompatibility. In vivo evaluation of the IBD model showed promising treatment efficacy of AHRG scaffolds.

Conclusion

The as-fabricated AHRG scaffolds effectively eliminated infection and inhibited biofilm formation. IBD repair was facilitated by the bactericidal properties and 3D porous structure of the AHRG scaffold, suggesting its potential in the treatment of IBDs.

Life and death of liquid-infused surfaces: a review on the choice, analysis and fate of the infused liquid layer

We review the rational choice, the analysis, the depletion and the properties imparted by the liquid layer in liquid-infused surfaces – a new class of low-adhesion surface.

Engineered 3D Polymer and Hydrogel Microenvironments for Cell Culture Applications

The realization of biomimetic microenvironments for cell biology applications such as organ-on-chip, in vitro drug screening, and tissue engineering is one of the most fascinating research areas in the field of bioengineering. The continuous evolution of additive manufacturing techniques provides the tools to engineer these architectures at different scales. Moreover, it is now possible to tailor their biomechanical and topological properties while taking inspiration from the characteristics of the extracellular matrix, the three-dimensional scaffold in which cells proliferate, migrate, and differentiate. In such context, there is therefore a continuous quest for synthetic and nature-derived composite materials that must hold biocompatible, biodegradable, bioactive features and also be compatible with the envisioned fabrication strategy. The structure of the current review is intended to provide to both micro-engineers and cell biologists a comparative overview of the characteristics, advantages, and drawbacks of the major 3D printing techniques, the most promising biomaterials candidates, and the trade-offs that must be considered in order to replicate the properties of natural microenvironments.